Intro and question..... (1 Viewer)

[Dangerson]

Hi all..... I've been lurking here watching and learning for a few months since I picked up my new-to-me 1997 Lexus LX450. I've been in a Chevy family all my life and joined the Toyota fan club when I bought my 1993 xtra cab new. I picked up this gem from a lady whose husband died unexpectedly back in April and he was about 95+% finished with the project. However, when I picked it up it was not running and I had to complete the upper part of the motor (intake, throttle body, EGR, air cleaner, MAF, etc) before I finally got it to turn over and run (shoutout to @slow95z for a replacement ECU). I have been daily driving her while baselining and learning the Land Cruiser specifics. It was a bit challenging finishing a project that I could not ask the previous owner questions. His work was good and I like most of the upgrades he did (lift, tires/wheels, dual battery, front/rear bumpers, winch, rear tire carrier, upgraded radiator, etc).

My question is one of lagging low to midrange power. I have searched the forum (and other LC forums), Googled, YouTubed, scanned the FSM.

Here is what is happening -- truck idles fine, truck can go down level roads fine. When I put a load on (an incline or tow a trailer) between 1000 and 3000 RPM, it lacks power. However, as the RPMs increase, once I hit between 3000 and 3200 or 3400, it is like a turbo button is hit (kinda like in a video game) and I get extra power and she pulls/accelerates up to 5000 RPM. I get this in all gears - not much noticeable in first, but definitely felt in 2nd, 3rd, and overdrive.

Here is what I've done -- baselining (changed air filter, oil, oil filter, fuel filter, etc), cleaned MAF, replaced TPS, checked CATS which appeared clear (although a clogged CAT would not allow for the higher RPM power), sprayed all vacuum lines with starter fluid (with no increase in engine idle RPM), adjusted throttle and transmission cables. The truck ran great yesterday morning on the way to breakfast, but the issue appears later on that morning. I am also getting a P0401 (EGR error) code about 80% of the time when I drive her (which I am working on). She's not overheating, and exhibits this behavior with/without PWR ECT button.

I am loading up the parts cannon, but I really think the key is the additional power that kicks in around 3000/3300 RPM. I am hoping there is some super secret Land Cruiser handshake that I need to learn that will fix this issue so I can enjoy my rig like the rest of y'all.

Thanks for reading,
.....Dan

 

[slow95z]

Have you checked the timing?

 

[OffRoadScott]

Does it feel like it is lagging when you step on the gas? Toyota transmissions can be very picky about the ATF put in them. In no way would I do a drain and flush, as it might make the transmission more prone to failure as the little material might be holding it together, if that makes sense.

If you do not know what fluid is in there exactly I would drain and fill with the recommend Toyota ATF and make sure you refill with the exact amount you removed.

If you know for a fact that the transmission does have the correct fluid, it could be a weight/gearing issue.

The Land Cruiser has 4.10 gears in it and perfect for the factory size. If you are running 35 or larger you have increased your overall tire size by 12%. If you re-gear there are a few options, underdrive and overdrive gears for the transfer case or re-gear the 3rds or you could do both. If you do both I wouldn't go any higher the 4.56 in the 3rds as the high range gears increase your ratios 10%. 4.56 and the transfer case gears would essentially put you near 5.0 in the 3rds and some people say which is ideal for 37s.

"These gears offer a 10% underdrive in high range, equivalent to converting axle gears from the 4.10 to 4.56 gears without having to do ring & pinion work." From Cruiser Teq website.

Sumo Gear Transfer Case Gears

 

[Dangerson]

Have you checked the timing?

My scanner says it is 4 or 4.5 degrees at 740 RPM. And when I rev the motor I can see it increase.

 

[gummycarbs]

I've been in a Chevy family all my life

My condolences.

I am also getting a P0401 (EGR error) code about 80% of the time when I drive her

You should focus on fixing that first. I wouldn't trust the starter fluid vacuum hose test, either. Just start replacing and cleaning if you don't know the last time they were done.

My scanner says it is 4 or 4.5 degrees at 740 RPM

Why 740 RPM? Idle should be 650 +/- 50 RPM when warm and in park or neutral.

Here's how to check the timing:

 

[mudgudgeon]

Have you checked / replaced the red dot?

Orange Dot Mod

If you take a look at your air flow meter, you'll probably find an old and worn out orange dot that was put on for some unknown reason as the car was being made. I think most people tend to neglect maintenance of this dot, so it's likely yours needs to be replaced. Here's how you do...

forum.ih8mud.com

 

[Dangerson]

Have you checked / replaced the red dot?

Orange Dot Mod

If you take a look at your air flow meter, you'll probably find an old and worn out orange dot that was put on for some unknown reason as the car was being made. I think most people tend to neglect maintenance of this dot, so it's likely yours needs to be replaced. Here's how you do...

forum.ih8mud.com

I'll do that after I finish with the muffler bearings.

 

[Dangerson]

My condolences.

At least it wasn't Ford.

You should focus on fixing that first. I wouldn't trust the starter fluid vacuum hose test, either. Just start replacing and cleaning if you don't know the last time they were done.

It appears the previous owner replaced the vacuum lines. I have extra lines that came with the vehicle so I'll check all those as well. I will be replacing the EGR valve today and I already cleaned out the EGR modulator. Agree that I should pursue elimination of the 401 code.

Why 740 RPM? Idle should be 650 +/- 50 RPM when warm and in park or neutral.

740 RPM because I hadn't let 'er warm up. Will recheck today.

Thanks for the comments and input.

 

[Rusty Marlin]

That 401 is a PITA. I gave up after cleaning everything, replacing all VSV and vacuum lines and finally just pulled the EGR and capped off the manifolds.

Oh, and in case no one has said if formally:

Welcome to MUD!

What are your plans for the rig? I noticed the mall crawler steps and am concerned about them getting ripped off or smashed flat on some adventure.

 

[Dangerson]

That 401 is a PITA. I gave up after cleaning everything, replacing all VSV and vacuum lines and finally just pulled the EGR and capped off the manifolds.

Oh, and in case no one has said if formally:

Welcome to MUD!

What are your plans for the rig? I noticed the mall crawler steps and am concerned about them getting ripped off or smashed flat on some adventure.

I was able to clear the 401 code today with a new EGR valve and checking all vacuum lines. Two test drives today code free!

I also replaced the downstream O2 sensor as well as continued my baselining by changing spark plugs. The old ones were gapped between 0.045 and 0.060 -- past the 0.031 called for by my Lexus LX450 FSM. New plugs are NGK Iridium gapped to 0.031 (+- 0.002).

At idle of 615 RPM she is timed at 4 degrees when at operating temp.

What I noticed while watching live data on my reader during the test drive is that I could consistently cause the surge in power in 2nd, 3rd, and OD at 3200 RPM (+- 100). Additionally, when that surge occurred, the volt reading on the downstream O2 sensor jumped from 0 or 0.010/0.015 to 0.800 or 0.900. I do not know if the volt increase is REFLECTING the additional fuel being added at 3200 RPM or CAUSING the additional fuel to be added. The upstream O2 sensor does not reflect this spike in voltage. This behavior was also going on with my old downstream O2 sensor. Just for fun, I also swapped in a spare ECU -- same behavior.

Thanks for noticing the mall crawler steps. This is an adventure rig to off road and tow our small travel trailer. Eventually those will come off, either voluntarily when I install the rock sliders that came with the vehicle, or involuntary on a trail.

 

[ppc]

At idle of 615 RPM she is timed at 4 degrees when at operating temp.

Are you still getting this measurement from the scan tool? If so, that is not the proper way to check/set timing. You have to set the ECM into "Base" mode and measure with a timing light as follows:

 

[Rusty Marlin]

Are you still getting this measurement from the scan tool? If so, that is not the proper way to check/set timing. You have to set the ECM into "Base" mode and measure with a timing light as follows:

View attachment 3112357

BTW, that SST is nothing but a "bent paper clip", so don't get wrapped too far around the axel if you didn't know what the SST is.

 

[mudgudgeon]

Are you still getting this measurement from the scan tool? If so, that is not the proper way to check/set timing. You have to set the ECM into "Base" mode and measure with a timing light as follows:

View attachment 3112357

@Dangerson You might benefit from more static advance too.
You can increase timing to up to 10⁰ BTDC.

increasing advance in mine gave it stronger pickup from idle, and stronger mid range pick up.

Not all 1fz-fe will tolerate 10⁰ advance. Some will ping with that much advance.
Set advance with timing light, and paperclip SST in the diagnostic port.

I don't know how changing timing advance affects smog test rules where you are

 

[GerhardUngerer]

I had just dealt with this in the past couple of weeks. First, the EGR modulator on mine went kaput. It had a hole burnt into it on the bottom. I put a new one in and it too went the same route. Turns out that those vacuum lines go brittle. So I replaced the line with a fresh one. That made the code go away, but didn't do much for the power. I replaced the PCV and voila! So, try those two things. Also, as stated above, you might want to adjust the timing.